Yeasts and moulds play a major role in spoilage of different types of dairy products, like yogurt, sweetened and sour cream and fresh and ripened cheese types and thus can lead to high economic losses. Chemical preservatives like organic acids and their salts (e.g. sorbate and propionate) are used to preserve dairy products and protect and prolong the shelf life. Drawbacks in using chemical preservatives are the labelling requirements (often as E numbers) and potential adverse effects on the sensory properties of the foodstuff.
In 1993 Valio, a finish dairy company described in EP 0576780 the use of a protective culture to inhibit fungal growth. The culture is a mixture of a Lactobacillus rhamnosus strain (deposited at Deutsche Sammlung von Mikroorganismen and Zellkulturen GmbH (DSM) with the deposition number DSM 7061) and a Propionibacterium freudenreichii subsp. shermanii strain (DSM 7067). The specific characteristic of this co-culture was that the combination of the Lactobacillus and the Propionibacterium had better antifungal activity than the Lactobacillus rhamnosus alone. The culture was commercialized by Wiesby under the name “Bio Profit” and renamed into HOLDBAC™ YM-B by Danisco.
EP 0576780 relates to a novel microorganism strain Lactobacillus casei ssp. rhamnosus LC-705, DSM 7061, having a yeast and mould controlling effect, to bacterial preparation comprising this strain, alone or in combination with a bacterium of the genus Propionibacterium or another strain of the bacterium Lactobacillus casei and/or with conventional agents used for yeast and mould control.
EP1308506 (Swiss Federal Institute of Technology (ETH) in Zürich, Switzerland) also describes the combination of lactobacilli and propionibacteria. A Lactobacillus paracasei subsp. paracasei strain (DSM 14514) from the ETH was commercialized as a blend with Propionibacterium freudenreichii subsp. shermanii DSM 7067 from Valio under the name HOLDBAC™ YM-C.
Patent WO 03/040349 relates to a mixture of bacteria being a non starter culture which is free from metabolites and comprising the species Propionibacterium jensenii and a second bacterium selected from the genus Lactobacillus. 
U.S. Pat. No. 4,728,516 relates to a method of inhibiting mould and psychrotrophic bacteria in creamed Cottage cheese using a mixture of Streptococcus lactis subspecies diacetylactis and Propionibacterium shermanii in the cream dressing or creamed Cottage cheese at refrigeration temperatures.
DE202006014937 relates to butterfat mixture with reduced fat content, comprises a butter and bio-protective cultures from lactic acid bacteria in the absence of preservatives.
U.S. Pat. No. 5,096,718A relates to metabolite material of propionibacteria as well as uses thereof for inhibiting the growth of gram negative psychrotrophic bacteria, yeast, mould, gram positive bacteria, or Listeria in food products.
WO9816124A1 relates to a food or beverage or animal feed composition which includes an antimycotic effective amount of propionibacteria metabolites.